1. Field of the Invention
This invention relates to a method for improving the quality of the fragrance of a perfume or a perfume composition (hereinafter, a perfume, for simplicity), and more specifically, to a method for improving the quality of the fragrance of a perfume by balancing the fragrance and maintaining the tenacity of the fragrance of the perfume by incorporating at least one perfume controlling agent in the perfume. This method improves the acceptability of the perfume by the user.
2. Description of the Prior Art
The quality of a perfume is determined by several factors. As far as its user acceptance is concerned, important factors are not only the actual odor characteristics and stability but also include the balance of the odor emission of and the tenacity of each component.
Generally, many natural or synthetic fragrant substances used as perfume materials degenerate or decay as a result of chemical changes such as polymerization, oxidation or decomposition due to the action of light, temperature, air, moisture, etc. Furthermore, they are available in a wide variety of forms ranging from low-viscosity liquids, high-viscosity resinous substances through pastes to solids. Accordingly, stabilizers must be added to chemically unstable fragrant substances, and suitable diluents must be used for high-viscosity or solid substances.
On the other hand, in order to create odors of superior quality, it is necessary to add to a perfume a substance having a fixing effect which controls the emission of odor of the fragrant substance so that a prescribed odor emission is always given off over a period of time.
Since these stabilizers, diluents and fixatives are used together with perfumes, naturally these materials must be completely safe with regard to skin irritation and toxicity, and preferably interact to reduce the skin irritation and toxicity of perfume compositions when they are incorporated therein.
Furthermore, from the viewpoint of controlling environmental pollution, these stabilizers, diluents and fixatives desirably should be biodegradable, i.e., highly assimilable by microorganisms, when discarded.
Conventionally in the production of perfumes, various controlling agents are added to perfumes in order to increase their fragrance characteristics and odor stability. In almost all cases, these controlling agents are used for a single purpose, for example, as stabilizers, diluents, or fixatives. These controlling agents are not always colorless, transparent, tasteless, and odorless compounds. Generally, odoriferous substances, such as benzyl alcohol or benzyl benzoate affect the creation of odors to a somewhat great extent. Propylene glycol, dipropylene glycol, diethyl phthalate, triethyl citrate, and isopropyl myristate, for example, are known as relatively odorless compounds, but are used only for a single purpose either as diluents or fixatives. They do not have a dual effect of stabilizing the perfumes and rendering them non-hazardous.
Propylene glycol and dipropylene glycol have low oral toxicity, and are among those perfume controlling agents which can be easily used. However, because of the comparatively high polarity of propylene glycol and dipropylene glycol, the ability to dissolve oil-soluble perfumes therein is reduced, and it is difficult to maintain a constant emission of fragrance.
The same can be said with regard to triethyl citrate. Although the oral toxicity of triethyl citrate is low, it has a high polarity like that of glycols, and is unsatisfactory in regard to the ability to dissolve oil-soluble perfumes and in regard to its fixing effect.
Diethyl phthalate is a very interesting material because its polarity is relatively suitable for use as a perfume controlling agent, and it acts both as a diluent and a fixative. However, from a safety standpoint, it has the disadvantage that its oral toxicity is high, and it is not easily biodegradable.
Isopropyl myristate has a low oral toxicity and good biodegradability, and is a superior perfume controlling agent from a safety standpoint. However, in contrast to glycols or triethyl citrate, it has so low a polarity that it has a markedly reduced ability to dissolve perfumes having a high polarity, and a uniform fragrance cannot be obtained.
Until now no ingredient which serves as a diluent, solubilizer, fixative and balancing agent with complete safety and which does not have any odor itself has been employed in perfumes to satisfy the above-mentioned requirements.
Methods are not yet known for improving the quality of the fragrance of a perfume by using perfume controlling agents which can be employed with a wide variety of perfumes.